The present invention relates to the air heater for recovering a heat of exhaust gas from an incinerator for disposing wastes. More particularly, the invention relates to an apparatus for heating air that is capable of recovering heat energy out of burnt exhaust gas of elevated temperature by heat exchange with air and hence of using the resultant heat energy to advantage, where exhaust gas occurs during incineration of wastes (in which are included combustibles of general wastes such as municipal wastes disposed of by households and offices and also of industrial wastes such as waste plastics, shredded car dusts, waste office equipment, waste electronic equipment, waste cosmetic containers and the like) in a incinerator for municipal wastes and in an incinerator for industrial wastes. The invention also relates to an apparatus for disposing of wastes which is provided with the above heating apparatus.
An incinerator for municipal wastes and an incinerator for industrial wastes have been equipped with an apparatus for heating high-temperature air in order to recover and utilize the heat energy of burnt gas of elevated temperature derived by incinerating those wastes. This heating apparatus of high-temperature air is so designed that heat is recovered by allowing air to flow through a heat transfer conduit formed of a metal, followed by heating of the air on heat exchange with the burnt gas of elevated temperature. The heat energy thus recovered is utilized as a heat source in decomposing wastes thermally, in generating electricity and in other systems.
In FIG. 49, there is shown one form of a conventional heating apparatus of high-temperature air. A burning melting portion 49 is located upwardly of a burning melting furnace 53, and a heating apparatus 1 of high-temperature air is disposed downwardly of that apparatus. In the burning melting portion 49, gas and air for use in combustion are supplied to a burner 56 so as to burn combustible components such as wastes at a high temperature of about 1300xc2x0 C. so that a melted slug 53f and a burnt exhaust gas G are generated. Usually, the burnt exhaust gas G contains dust (refuse) and constitutes a highly corrosive gas including corrosive materials such as chlorine and hydrogen chloride which, however, depend on the kind of wastes. In such furnace, the burnt exhaust gas flows at a temperature of 1000-1100xc2x0 C. and at a flow rate of about 2-3 m/sec. The heating apparatus 1 of high-temperature air is essentially constructed with a heat transfer conduit 9 arranged to recover the heat from the burnt exhaust gas G of high temperature stated above. For the heating apparatus 1 of high-temperature air to entrap heated air in a large quantity, the heat transfer conduit 9 is structured to be elongate and is usually disposed in a plurally paralleled posture.
It is required, therefore, that such heat transfer conduit located in the incineration furnace and exposed to a high temperature and to a highly corrosive gas atmosphere should be sufficiently durable, in respect of both the material and the structure, with respect to the corrosive gas of elevated temperature noted above. As means for imparting improved corrosion resistance to the heating apparatus of high-temperature air, it is thought that a stud pin could be welded to the heat transfer conduit formed of a metal, and an castable refractory material could be placed in surrounded relation to that pin and that refractory bricks basically of a rectangular parallelopiped shape could be arranged with their joints connected lengthwise and widthwise. These systems permit such a refractory material to act as a physical barrier against convection and mutual diffusion in a corrosive gas phase, and therefore, can somewhat prevent the heat transfer conduit from getting corroded.
Problems to be Solved by the Invention
However, each such system leads to cracked refractory material, eventually resulting in corroded and impaired fixing jig for the refractory material, or in damaged and detached refractory material itself, because of the difference in thermal expansion which arises from combination of different materials between the refractory material and the metallic heat transfer conduit. This causes a serious corrosion phenomenon in which the metallic heat transfer conduit becomes corrosively damaged, creating the problem that the heating apparatus of high-temperature air suffers from shortened service life and hence from reduced working efficiency with consequent decline in the efficiency of heat recovery upon heat exchange.
Moreover, the heat transfer conduit has the problem that it is rather elongate and hence liable to be thermally deformable and bendable. Another problem is that since a plurality of heat transfer conduits are disposed in parallel to each other, dust contained in an exhaust gas gets deposited between those conduits, thus inviting reduced efficiency of heat recovery based on heat exchange.
One object of the present invention is to attain prolonged service life in an apparatus for heating high-temperature air and also to make the apparatus highly efficiently workable, thereby gaining improved efficiency of heat recovery through heat exchange. For other objects, the invention provides an apparatus for heating high-temperature air which is less thermally deformable and less susceptible to dust deposition, and further an apparatus for disposing of wastes which is provided with such heating apparatus.
Disclosure of the Invention
In order to achieve the foregoing objects, the present invention is constructed as will be described hereinbelow.
In the invention recited in claim 1, there is provided an apparatus for heating high-temperature air characterized in that such appratus is located for use in an atmosphere containing a gas of elevated temperature and has a heat transfer conduit disposed to heat, by means of heat exchange with the gas of elevated temperature, air to be heated and caused to flow through the heat transfer conduit, and such heat transfer conduit comprises a heat transfer pipe arranged to flow the air to be heated therethrough, and a refractory protective pipe formed of a refractory material and held in coaxially covered relation to the heat transfer pipe with a gapping defined between the protective pipe and the heat transfer pipe.
According to this invention, the heat transfer pipe (usually formed of a metal) and the refractory protective pipe formed of a refractory material are less susceptible, by the provision of such gapping, to mutual propagation of those effects attributable to different thermal expansion of the different materials used for formation of both pipes. This makes it possible to reduce damaged and detached portion of the refractory material which tends to result from such varied thermal expansion.
In the invention recited in claim 2, there is provided an apparatus for heating high-temperature air characterized in that such apparatus is located for use in an atmosphere containing a gas of elevated temperature and has a heat transfer conduit disposed to heat, by means of heat exchange with the gas of elevated temperature, air to be heated and flowing through the heat transfer conduit, and such heat transfer conduit comprises an inner heat transfer pipe formed of a metal and opened at a tip thereof, and an outer heat transfer pipe formed of a refractory material and held in coaxially covered relation to the inner metallic heat transfer pipe with a spacing defined between the outer and inner pipes, and after being caused to flow through the inner metallic heat transfer pipe, the air to be heated is heated with the gas of elevated temperature while the former air is being passed at from the open tip of the inner pipe through the spacing between the inner and outer pipes.
In this invention, damaged and detached portion of the refractory material due to the different thermal expansion stated above can likewise be reduced by the provision of such gap passage.
The invention recited in claim 3 is as set forth in claim 1 or 2 and is characterized in that the refractory protective pipe or the outer refractory heat transfer pipe is structured to have an angular face in cross section, and the heat transfer conduit is disposed in a plural number and fixed in face-to-face contact with the adjoining protective pipe or heat transfer pipe at its sectional angular face.
According to this invention, the refractory protective pipe or the outer refractory heat transfer pipe is formed to be angular in a tetrahedral shape or the like when seen cross-sectionally, and the heat transfer conduit is disposed in a plural number and fixed in face-to-face contact with the adjoining protective pipe or heat transfer pipe. Therefore, the heating apparatus of high-temperature air so constructed leads to improved structural rigidity, resulting in a marked decrease in the thermal decomposition discussed above. Furthermore, such face-to-face arrangement renders the apparatus flat throughout the surface thereof and hence less prone to dust deposition on the surface than an arrangement having a concave and convex surface so that the efficiency of heat transfer can be maintained on a high level and over an extended period of time.
The invention recited in claim 4 is as set forth in claim 1 or 3 and is characterized in that the heat transfer pipe of the heat transfer conduit comprises an inner heat transfer pipe formed of a metal, and an outer heat transfer pipe formed of a metal and held in covered relation to the inner metallic heat transfer pipe with a spacing defined between the two pipes, the air to be heated is heated with the gas of elevated temperature while the former air is being passed through the spacing disposed between the inner and outer pipes, and such refractory protective pipe is arranged to cover the outer metallic heat trandfer pipe and disposed coaxially of the latter pipe with a gapping defined between the protective and outer pipes.
The invention recited in claim 5 is as set forth in claim 1 or 3 and is characterized in that the heat transfer pipe of the heat transfer conduit comprises an outer heat transfer pipe formed of a metal, and an inner pipe arranged to communicate with one end of the outer pipe with a spacing defined between the outer and inner pipes, the inner pipe is formed into a thermally insulated structure with a lower thermal conductivity than the metal, and the air to be heated is heated with the gas of elevated temperature along an outer wall of the outer metallic heat transfer pipe while the former air is being passed through the spacing defined between the outer metallic heat transfer pipe and the inner thermal insulating pipe.
According to these inventions, the air to be heated is heated alone which is allowed to flow through the spacing defined between the outer metallic heat transfer pipe and the inner thermally insulating pipe, but the air being passed through the inner thermally insulating pipe is not heated together with the former air. Namely, the air present in the inner pipe is thermally isolated such that the temperature change of the air to be heated in the inner pipe is held to so small an extent as to be acceptable. Enhanced heat transfer efficiency as well as simplified temperature control is thus feasible.
More specifically, with use of the heat transfer conduit constructed such that the heat of the gas of elevated temperature is recovered by allowing air to be heated to flow through the spacing defined between the outer metallic heat transfer pipe and the inner heat transfer pipe, followed by discharging of the resultant heat through the inner heat transfer pipe at from the one end thereof made to communicate with the outer heat transfer pipe, or with use of the heat transfer conduit constructed such that the heat recovery is effected by flowing the air in a reverse direction, the heat of the gas of elevated temperature is recovered by the air being flowed in the spacing between such outer and inner pipes and along the metallic wall of the outer pipe. In this case, the recovered heat gets transmitted along the metallic wall of the inner heat transfer pipe up to the air flowing through such inner pipe. For that reason, conventional practice has the problem that the air present in the inner heat transfer pipe is markedly changeable in temperature, and the air to be heated when taken outside is variable in temperature, the efficiency of heat transfer being thus difficult to obtain as desired. In order to gain desired heat transfer efficiency, the air present in the outer heat transfer pipe located outwardly of the inner heat transfer pipe is required to be unnecessarily higher. This invites a small temperature difference between a gas of elevated temperature and an air in the outer heat transfer pipe with eventual need for a wide area of heat transfer, forcing conventional practice to employ an apparatus of a large scale. The present invention is so constructed that the heat of a gas of elevated temperature is transmitted solely to an air to be heated and caused to flow through the spacing between the outer metallic heat transfer pipe and the inner thermally insulating pipe. That is to say, such gas heat can be prevented from transmission up to an inner wall of the inner pipe. Hence, a desirable efficiency of heat transfer is obtainable.
The invention recited in claim 6 is as set forth in claim 5 and is characterized in that the inner pipe is formed of a thermally insulating material of low thermal conductivity other than a metal. The invention recited in claim 7 is characterized in that the inner pipe is brought into a thermally insulated structure in which the thermally insulating material is sandwiched with metallic tubes. The invention recited in claim 8 is characterized in that the inner pipe is brought into a thermally insulated structure in which such pipe is formed of a metal and in a double-piped vacuum-drawn arrangement. In the invention recited in claim 9, the thermal insulating material is specified to be ceramics. A highly thermally insulating material such as for example ceramics is used, as claimed, as a material itself for formation of the inner pipe so that structural simplicity is attained.
The invention recited in claim 10 is as set forth in any one of claims 4-9 and is characterized in that the air to be heated is caused to flow in a direction reverse to that of the gas of elevated temperature through the spacing between the inner pipe and the outer pipe, both of which pipes are arranged to constitute the heat transfer conduit. This is conducive to improved efficiency of heat transfer.
The invention recited in claim 11 is as set forth in any one of claims 1, 3-9 and is characterized in that a plurality of support materials are fixedly placed outwardly of the heat transfer pipe to thereby support the refractory protective pipe.
These support materials allow the gapping between the heat transfer pipe and the refractory protective pipe to be substantially uniform throughout the length thereof. As a consequence of provision of the support materials, even if such conduit and pipe are elongate, they are free from fear of being in partial contact with each other. Additionally, the refractory protective pipe of great mass can be held in firmly supported relation to the heat transfer pipe with the result that the former pipe is less likely to become unstable.
The invention recited in claim 12 is as set forth in any one of claims 4-11 and is characterized in that the gapping is defined to communicate with a passageway for flow of the air to be heated with a through hole made in a wall of the outer metallic heat transfer pipe.
This construction imparts to the gapping a positive pressure with respect to the external atmosphere, thus decreasing a tendency for the gas of elevated temperature to intrude from the outside into the refractory protective pipe. The outer metallic heat transfer pipe can thus be reliably prevented from getting corrosively deteriorated.
The invention recited in claim 13 is as set forth in any one of claims 1-12 and is characterized in that a partitioned gapping is defined at a region where a tip of the heat transfer pipe is opposed to a tip of the refractory protective pipe or the refractory heat transfer pipe, and the air to be heated is introduced into such space partitioned at the pipe tips. The same beneficial effects as in the invention of claim 12 are obtainable also in the partitioned space.
The invention recited in claim 14 is as set forth in any one of claims 4-11 and is characterized in that means is disposed for introducing extraneous air into the gapping between the refractory protective pipe and the outer metallic heat transfer pipe.
In this invention, because the extraneous air is introduced into the gapping between the refractory protective pipe and the outer metallic heat transfer pipe, a corrosive gas can be completely avoided from becoming reversely diffused toward and intermixed with the air to be heated as would be encountered in purging the corrosive gas by leakage of the air to be heated out of an opening made in a wall of the heat transfer pipe. This reveals enhanced anticorrosion and improved reliability concerning the associated apparatus.
The invention recited in claim 15 is as set forth in claim 14 and is characterized in that a partitioned gapping is defined at a region where a tip of the outer metallic heat transfer pipe is opposed to a tip of the refractory protective pipe, and the extraneous air is introduced into such gapping partitioned at the pipe tips. The same beneficial effects as noted in the invention of claim 14 are attained also in the partitioned gapping.
The invention recited in claim 16 is as set forth in any one of claims 1-15 and is characterized in that the tip of the refractory protective pipe or the outer refractory heat transfer pipe is formed in a convex shape so as to be less resistant to gas flow of elevated temperature.
In this invention, such convex tip has a role to relax those thermal effects of concentrated thermal stress and the like arising from contact of the refractory protective pipe or the outer refractory heat transfer pipe with the gas flow of elevated temperature, eventually leading to reduced damage of wear and breakage as to the top end of either of such pipes.
The invention recited in claim 17 is as set forth in claim 16 and is characterized in that the convex shape is of a hemispherical shape. This hemispherical shape makes it possible to uniformly distribute those thermal effects having produced on the tip, contributing to further reduced damage to the tip.
Additionally, the convex shape may be a conical shape as in the invention recited in claim 18 and a polyhedral convex shape as in the invention recited in claim 19. The conical shape stated here includes a shape in which the top end is chamfered, and the polyhedral convex shape stated here denotes a convexity shaped to have a polyhedron such as a polypyramid, a polygon or the like. In brief, the convex shape may be of a convexity shaped by a planar face and either one or both of curved faces as in the invention recited in claim 20, and no particular restriction should be imposed on the convex shape. A convexly streamlined shape may also be included.
The invention recited in claim 21 is as set forth in any one of claims 16-20 and is characterized in that the refractory protective pipe or the outer refractory heat transfer pipe of the heat transfer conduit is shaped like a circular pillar when seen outwardly sectinonally, and either such pipe is formed to be smoothly extensive from its convex tip to its base portion. The invention recited in claim 22 is as set forth in any one of claims 16-20 and is characterized in that the refractory protective pipe or the outer refractory heat transfer pipe of the heat transfer conduit is shaped like a tetrahedral pillar when seen outwardly sectinonally, and either such pipe is formed to be smoothly extensive from its convex tip to its base portion. Here, the smoothly extensive structure is exemplified to be obtainable as by chamfering. This structure can decrease those stepped or angular portions tending to take place from the tip to the base, alleviating the problems of wear and damage of the above pipe which would result from contact with the gas of elevated temperature flowing at a high speed.
The invention recited in claim 23 is as set forth in any one of claims 1-15 and is characterized in that the tip of the refractory protective pipe or the outer refractory heat transfer pipe is formed as a refractory removable cap member.
Therefore, even when the cap member is centrally worn or damaged due to collision with the burnt exhaust gas of elevated temperature caused to flow at a high speed, such cap is easily replaced by a new one.
Now, in the case where the outer metallic heat transfer conduit is constructed with the refractory protective pipe located to flow the air to be heated therethrough, the protective pipe disposed to cover the heat transfer pipe with the gapping defined between the two pipes, and the cap member is screwed with the space provided at a region where the tip of the protective pipe is opposed to the tip of the heat transfer pipe, and in the case where the outer metallic heat transfer pipe is provided with a through hole for the air to be heated and caused to pass therethrough to be partly flowed into the gapping, such cap is spirally secured, i.e., fixedly screwed. The cap is therefore held by means of spiral line contact. This means that no particular stress concentration is existent even if the temperature change (thermal cycling) is present between room temperature and high temperature, and detachment and damage are less likely to take place. Since, moreover, the gapping can be so made in its inside as to have a positive pressure, the gas of elevated temperature is prevented against intrusion from the outside into the refractory protective pipe and the refractory cap member. Also with this point taken in view, part of the refractory material can be alleviated from being impaired, and prolonged cycle of replacement is rendered possible.
To form the cap member into a rotatably screwing type, it is required that, in the case where the heat transfer conduit is arranged in a plural number and on a parallel with each other with no gap left therebetween and with the refractory protective pipe or the outer refractory heat transfer pipe longitudinally positioned in parallel with the direction of gas flow, the outside diameter of the cap member be so decided that the caps of two adjacent heat transfer conduits are not impinged on each other during rotation thereof.
The invention recited in claim 24 is as set forth in claim 23 and is characterized in that the cap member is formed in a convex shape so as to be less resistant to flow of the gas of elevated temperature. By use of this convex cap, those impacts brought about by gas flow of elevated temperature are relaxed so that the cap itself is prevented from wear and damage, and the cycle of replacement is prolonged.
The invention recited in claim 25 is as set forth in claim 23 or 24 and is characterized in that the cap member is screwed to the tip of the heat transfer pipe with a gapping defined at an opposed tip portion, the screwing is effected with a partial gap, and the heat transfer pipe is provided atits tip with a through hole for the air to be heated and caused to pass therethrough to be partly flowed into the gapping. Because the gapping at the screwed portion can be so made in its inside as to have a positive pressure with respect to the external atmosphere, the gas of elevated temperature is prevented against intrusion from the outside into the refractory cap member and subsequent contact with the metallic heat transfer pipe at the screwed portion.
The invention recited in claim 26 is as set forth in any one of claims 23-25 and is characterized in that the refractory protective pipe or the outer refractory heat transfer pipe of the heat transfer conduit is shaped like a circular pillar when seen outwardly sectinonally, and the cap member and either such pipe are connected to each other in an externally smoothly extensive manner. The invention recited in claim 27 is as set forth in any one of claims 23-25 and is characterized in that the refractory protective pipe or the outer refractory heat transfer pipe of the heat transfer conduit is shaped like a tetrahedral pillar when seen outwardly sectionally, and the cap member and either such pipe are connected to each other in an externally smoothly extensive manner. Here, the externally smoothly extensive shape is obtainable by forming such cap and pipe to have the same outside diameter, or by chamfering such cap and pipe when they are different in outside diameter.
The invention recited in claim 28 is as set forth in any one of claims 1-27 and is characterized in that the apparatus for heating high-temperature air comprises a first air heater positioned upstream of a passage for flow of the gas of elevated temperature, wherein a second air heater positioned downward of such flow passage, the air to be heated is supplied to and heated in the second air heater, and the resultant air is then transported to and heated in the first air heater.
The invention recited in claim 29 is as set forth in claim 28 and is characterized in that the apparatus for heating high-temperature air comprises a first air heater positioned upstream of a passage for flow of the gas of elevated temperature, and a second air heater positioned downward of such flow passage, the air to be heated is supplied to and heated in the first and second air heaters, respectively, and the two sorts of air heated are combined together and then taken outside.
In the apparatus for heating high-temperature air constructed as set forth in claim 28 or 29, the heat transfer conduit can be made short in length and light in weight. This makes the associated suspension support structure relatively light in weight and moreover permits simple operation when in dismantling the heat transfer conduit from the flow passage for the gas of elevated temperature during maintenance. Namely, the present invention enables the heat energy of the gas of elevated temperature to be recovered by the use of air, and the apparatus for heating high-temperature air for use of the heat energy to advantage can lead not only to shortened length per one heat transfer conduit and simplified support structure and maintenance operation, but also to simplified installation in terms of space and precision and reduced deformation arising from thermal strain. Thus, improved efficiency of heat transfer is attained.
In the apparatus for heating high-temperature air set forth in claim 28, low-temperature air to be heated is supplied to and heated in the second air heater. The outer heat transfer pipe and the inner heat transfer pipe, both of which are arranged to constitute the second air heater, are made to communicate with each other at one end of each pipe, specifically at a lower end of each pipe. The low-temperature air to be heated is selectively heated by either one of a system in which such air is supplied through the inner pipe to and heated in the outer pipe, and a system in which such air is supplied through the outer pipe to and heated in the inner pipe. The former system may be preferred from the point of view of thermal efficiency.
After being heated at a given temperature in the second air heater as stated above, the air to be heated is heated by either one of a system in which such air is supplied through the first air heater-constituting outer heat transfer pipe to and heated in the inner tube, and a system in which such air is supplied through the inner pipe to and superheated in the outer tube. The latter system may desirably be employed.
On the other hand, in the apparatus for heating high-temperature air set forth in claim 29, the low-temperature air to be heated is supplied to and heated in the first air heater and the second air heater, respectively. With use of the apparatus for heating high-temperature air thus constructed, the area for the flow passage of the air to be heated can be made greater than that of the gas of elevated temperature with eventual decline in pressure loss of the air to be heated. In such instance, the low-temperature air to be heated is heated by selecting either one of a system in which such air is supplied through the second air heater-constituting inner pipe to and heated in the outer heat transfer pipe, and a system in which such air is supplied through the outer heat transfer pipe to and heated in the inner pipe. When thermal efficiency is taken in view, the former system may be desired. The air to be heated and conveyed to the first air heater is heated, as in the second air heater, by selecting either one of a system in which such air is supplied through the inner pipe to and heated in the outer heat transfer pipe, and a system in which such air is supplied through the outer heat transfer pipe to and heated in the inner pipe. The latter system of the two selections is liable to suffer from increased temperature of the air at an inlet of the gas of elevated temperature, increased temperature of the pipe walls and increased temperature of the refractory material. In view of durability, therefore, the former system may be suitably selected.
The invention recited in claim 30 is as set forth in claim 29 and is characterized in that the air to be heated is partly supplied through either one of the first air heater-constituting heat transfer pipe or outer pipe and the inner pipe to and heated in either the inner pipe or the outer pipe, and the remaining portion of the the air to be heated is supplied through either one of the second air heater-constituting heat transfer pipe or outer pipe and the inner pipe to and heated in either the inner pipe or the outer pipe.
The invention recited in claim 31 is directed to the structure of a partition wall for use in an heat exchanger, which partition wall is disposed to separate an air passage from an exhaust gas passage, characterized in that the partition wall comprises a metallic wall placed in contact on one side with the air passage, and a refractory wall placed in contact on one side with the gas passage, a first gapping is defined between the other side of the metallic wall and the other side of the refractory wall and made to communicate with a through hole made in the metallic wall, thereby flowing burnt exhaust gas containing corrosive components and dust into the exhaust gas passage, and a plurality of support materials are securely attached to the other side of the metallic wall so as to support the refractory wall. The invention recited in claim 32 is as set forth in claim 31 and is characterized in that a second gapping is defined between the support materials and the refractory wall and made to communicate with the first gapping.
By the provision of these support materials, the gapping between the metallic wall and the refractory wall can be rendered substantially uniform throught the length thereof, and the refractory wall of great mass can also be held in firmly supported relation to the metallic wall. This gives least fear of the refractory wall becoming unstable. Further, since the air is flowed via the through hole into both the first gapping and the second gapping, the gas of elevated temperature can be prevented from intrusion into these spacings, and the metallic wall and the support materials can be reliably avoided from corrosion. Hence, the metallic wall and the like are noticeably prolonged in service life. In addition, the metallic wall is less corrosive even at high temperature so that it is possible to heat air at high temperature by heat exchange with a larger quantity of heat than is in conventional practice. Energy efficiency can thus be improved as to the finished apparatus on the whole.
In the invention recited in claim 33, there is provided a process for producing a partition wall for use in a heat exchanger wherein the partition wall is disposed to separate an air passage from an exhaust gas passage, the partition wall comprising a metallic wall placed in contact on one side with the air passage, and a refractory wall placed in contact on one side with the gas passage, a first gapping is defined between the other side of the metallic wall and the other side of the refractory wall and made to communicate with a through hole made in the metallic wall, thereby flowing burnt exhaust gas containing corrosive components and dust into the exhaust gas passage, and a plurality of support materials are securely attached to the other side of the metallic wall so as to support the refractory wall, characterized in that such process comprises the steps of disposing an interlaminar material over the other side of the metallic wall by covering vinyl sheet or paper tape thereover, or by coating tar or paint thereover, coating or spraying over the interlaminar material a water-containing castable material in a predetermined thickness, heating the castable material to dry and calcinate the same to thereby form the refractory wall and to remove the interlaminar material therefrom, and subsequently defining the first gapping on the refractory wall where the interlaminar material has been removed.
The invention recited in claim 34 is as set forth in claim 33 and is directed to the process for producing the partition wall wherein a second gapping is defined between the support materials and the refractory wall and made to communicate with the first gapping, characterizied in that such process comprises the steps of disposing an interlaminar material over the support materials, prior to or after welding of the the support materials to the metallic wall, by winding insulating tape made of polyvinyl chloride thereover, by covering vinyl hose cut short thereover, by coating aqueous paint thereover, or by immersing the support materials in stock solution of the aqueous paint, coating or spraying over the interlaminar material a water-containing castable material in a predetermined thickness, heating the castable material to dry and calcinate the same to thereby form the refractory wall and to remove the interlaminar material therefrom, and subsequently defining the second spacing on the support materials where the interlaminar material has been removed.
By use of these processes, a heat exchanger can be produced as desired by the present invention.
In the invention recited in claim 35, there is provided an apparatus for disposing of wastes which is provided with a thermal decomposition reactor in which wastes are thermally decomposed to generate a thermally decomposed gas and a thermally decomposed residue, a separator in which the thermally decomposed residue is separated into combustible components and incombustible components, a burning melting furnace in which the thermally decomposed gas and the combustible components are burnt at a temperature at which to melt ash to thereby discharge incombustible matter as melted slug, and an apparatus for heating high-temperature air in which the heat of gas of elevated temperature is recovered by heat exchange with air, characterized in that such apparatus for heating high-temperature air is as set forth in any one of claims 1-30. This apparatus for disposing of wastes can be improved in its operating efficiency in line with improved operating efficiency of the apparatus for heating high-temperature air.